Moisture removal apparatus

ABSTRACT

The apparatus comprises a pair of heat exchangers and a vortex tube which provides both hot and cold air from a source of compressed air. The cold air is used on one heat exchanger to freeze the moisture out of the gas and after ice has built up in the heat exchanger hot air is introduced to melt the ice. During this melting period the wet gas and the cold air are passed through the other heat exchanger.

United States Patent [72] Inventor Dan Paul Manka [56] References Cited msburghi UNITED STATES PATENTS 5; Qff gg'gi 2,581,168 1 1952 Bromley 62/5 b gf 1 3 2,737,028 3/1956 Machlanski 62/5 7 v [73] Assignee Jones & Laughlin Steel Corporation g g Pittsburgh, Pa

Primary Examiner-William J. Wye Attorneys-G. R. Harris and T. A. Zalenski ABSTRACT: The apparatus com rises a air of heat exchand b h'h d b hh d ld' gers an a vortex tu e w 1c prov1 es 0t 0! an co air [54] y8 fi M APPARATUS from a source of compressed air. The cold air is used on one aims rawmg heat exchanger to freeze the moisture out of the gas and after [52] U.S. Cl 1 62/5 ice has built up in the heat exchanger hot air is introduced to [51] Int.Cl F25b 9/02 melt the ice. During this melting period the wet gas and the [50] Field of Search 62/5 cold air are passed throu h the other heat exchanger.

PATENTEU Jun H971 3,581,509

INVENTOR.

DAN P. MANKA BY his ATTORNEY MOISTURE REMOVAL APPARATUS In many metallurgical operations continuous analysis of off gas is employed as a control means. Such gas frequently contains moisture, usually in fluctuating amounts. Calculation and utilization of the concentrations of the components of the gas are facilitated when they are based on a dry gas. Normally, the amount of gas required for analysis is only a few cubic feet per hour but for some purposes this must be moisture-free to an exceedingly low level, that is to say, a moisture concentration of a few parts per million. Further, it is frequently the case that moisture removal must be effected in rather close proximity to the apparatus being controlled-a blast furnace, basic oxygen steelmaking furnace or the like-in surroundings and under conditions unfavorable to the operation and maintenance of precision equipment.

It is an object of my invention therefore to provide apparatus for removing moisture to a very low level from a wet gas stream which is to be analyzed. lt is another object to provide such apparatus which effects continuous removal of moisture. It is another object to provide such apparatus which operates by freezing out the moisture and then melting the solid frozen product. It is still another object to provide such apparatus which operates satisfactorily in a mill atmosphere under mill conditions. Other objects of my invention will appear from the description thereof which follows.

I have invented a simple and effective apparatus containing no moving parts suitable for the objects above mentioned. It is operated by compressed air and utilizes a vortex tube to provide the cold and heat necessary for continuous operation. An embodiment of my invention presently preferred by me is illustrated in the attached schematic figure to which reference is now made.

My apparatus is intended to lower the moisture content of gas to the parts per million range, as I have mentioned. It is convenient to remove the bulk of the moisture, down to about 1 percent, by conventional means. The wet gas containing 1 percent or so of moisture is introduced into my apparatus through pipe 1 which branches into pipes 2 and 3 which, in turn, lead into heat exchangers 6 and 7, respectively. Pipe 2 is provided with a valve 4 and pipe 3 with a valve 5. Moisturefree gas from heat exchanger 6 is delivered through pipe 8 to gas outlet pipe 12 and from heat exchanger 7 through pipe 9 also to gas outlet pipe 12. Pipe 8 is provided with valve 10 and pipe 9 is provided with valve l1.

Heat exchangers 6 and 7 are provided with hot and cold heat exchange gas, preferably air, from vortex tube 14 in the way to be described. The vortex tube 14, which is also known as a Ranque-Hilsch tube, is of the same type as that shown in U.S. Pat. No. 1,952,28l, and is commercially available. Compressed air from a source not shown is introduced into the vortex tube 14 through inlet 15. The action of the vortex tube, which is described in the patent above mentioned, separates the incoming air into a cold fraction which is discharged through pipe 16 and a hot fraction which is discharged through pipe 23. Pipe 16 is connected to a heat transfer coil 17 inside heat exchanger 6 through valve 18. The other end 19 of heat exchanger coil 17 is open to the atmosphere. Hot air pipe 23 is connected through valve 20 to a heat exchanger coil 21 inside heat exchanger 7. The other end 22 of heat exchanger coil 21 is open to the atmosphere.

Pipe 23 on the upstream side of valve 20 is connected to pipe 24 which in turn is connected through valve 25 to pipe 16 on the downstream side of valve 18. Pipe 16 on the upstream side of valve 18 is connected through valve 26 and pipe 27 to pipe 23 on the downstream side of valve 20. Heat exchanger 6 is provided at its bottom with a drain valve 29 and heat exchanger 7 at its bottom with a drain valve 30.

The operation of my apparatus will now be described with respect to the figure. Vortex tube 14 is supplied through inlet 15 with compressed air under a pressure preferably of 40 pounds or more per square inch. It is: not necessary that the air pressure exceed about pounds per square inch. The vortex tube 14 requires this air in the amount only of about 2 cubic feet per minute to dry cgas at the rate of about 70 cubic feet per hour. The cold air ischarged through pipe 16 has a temperature in the neighborhood of -30 F. and this cold air, with valve 18 open and valve 26 closed, passes through coil 17 and into the atmosphere from its open end 19.

Wet gas to be analyzed is introduced into heat exchanger 6 by opening valve 4 in pipe 2 and closing valve 5 in pipe 3. The wet gas impinges on the cold surface of heat exchanger coil 17 and the moisture freezes thereon. The substantially moisturefree gas is withdrawn through pipe 8 and open valve 10 into pipe 12. Valve 9, ofcourse, is closed.

When coil 17 is covered with ice to the point that heat transfer from the gas drops off valve 18 is closed and valve 25 is opened. This allows hot air from pipe 23 to flow through coil 17 and out its open end 19, melting the frozen moisture on coil 17. Drain valve 29 is opened and the melted moisture flows out. While this defrosting is taking place, valve 4 is closed and valve 5 is open so that the wet gas is introduced into heat exchanger 7. Likewise, valve 20 is closed and valve 26 is opened so that cold air from vortex tube 14 passes into heat exchanger coil 21. The gas stream is thus continuously dehydrated either in heat exchanger 6 or heat exchanger 7 and the frozen moisture is melted in the heat exchanger not in use.

lclaim:

1. Apparatus for removing moisture from a gas to be analyzed comprising a heat exchanger, means for introducing wet gas to be analyzed into the heat exchanger and means for withdrawing dry gas to be analyzed therefrom, a vortex tube, means for introducing a heat exchange gas under pressure into the vortex tube, means for selectively conducting cold heat exchange gas from the vortex tube into the heat exchanger to freeze moisture out of the wet gas to be analyzed and hot heat exchange gas from the vortex tube into the heat exchanger to melt the frozen moisture therein.

2. Apparatus for removing moisture from a gas to be analyzed comprising first and second heat exchangers, means for introducing wet gas to be analyzed alternately into the first and the second heat exchangers, means for withdrawing dry gas to be analyzed alternately from the first and the second heat exchangers, a vortex tube, means for introducing a heat exchange gas under pressure into the vortex tube, means for conducting cold heat exchange gas from the vortex tube alternately to the first and the second heat exchangers to freeze moisture out of the gas to be analyzed, means for conducting hot heat exchange from the vortex tube alternately to the second and the first heat exchangers to melt the frozen moisture therein, and means for withdrawing moisture alternately from the second and the first heat exchangers. 

1. Apparatus for removing moisture from a gas to be analyzed comprising a heat exchanger, means for introducing wet gas to be analyzed into the heat exchanger and means for withdrawing dry gas to be analyzed therefrom, a vortex tube, means for introducing a heat exchange gas under pressure into the vortex tube, means for selectively conducting cold heat exchange gas from the vortex tube into the heat exchanger to freeze moisture out of the wet gas to be analyzed and hot heat exchange gas from the vortex tube into the heat exchanger to melt the frozen moisture therein.
 2. Apparatus for removing moisture from a gas to be analyzed comprising first and second heat exchangers, means for introducing wet gas to be analyzed alternately into the first and the second heat exchangers, means for withdrawing dry gas to be analyzed alternately from the first and the second heat exchangers, a vortex tube, means for introducing a heat exchange gas under pressure into the vortex tube, means for conducting cold heat exchange gas from the vortex tube alternately to the first and the second heat exchangers to freeze moisture out of the gas to be analyzed, means for conducting hot heat exchange from the vortex tube alternately to the second and the first heat exchangers to melt the frozen moisture therein, and means for withdrawing moisture alternately from the second and the first heat exchangers. 